Druid and Superset require a relational data store to store metadata. To use Postgres for
this, install Postgres and create a database for the Druid metastore. If you have already done
this using MySQL, you do not need to configure additional metadata stores in Postgres.

Steps

Log into Postgres:

sudo su postgres
psql

Create a database, user, and password called druid, and assign
database privileges to the user druid.